As is known, many food products, such as fruit juice, pasteurized or UHT (ultra-high-temperature treated) milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material.
A typical example of this type of package is the parallelepiped-shaped package for liquid or pourable food products known as Tetra Brik Aseptic (registered trademark), which is made by folding and sealing laminated strip packaging material.
The packaging material has a multilayer structure substantially comprising a base layer for stiffness and strength, which may comprise a layer of fibrous material, e.g. paper, or of mineral-filled polypropylene material; and a number of layers of heat-seal plastic material, e.g. polyethylene film, covering both sides of the base layer.
In the case of aseptic packages for long-storage products, such as UHT milk, the packaging material also comprises a layer of gas- and light-barrier material, e.g. aluminium foil or ethyl vinyl alcohol (EVOH), which is superimposed on a layer of heat-seal plastic material, and is in turn covered with another layer of heat-seal plastic material forming the inner face of the package eventually contacting the food product.
As is known, packages of this sort are produced on fully automatic packaging machines, on which a continuous tube is formed from the web-fed packaging material; the web of packaging material is sterilized on the packaging machine, e.g. by applying a chemical sterilizing agent, such as a hydrogen peroxide solution, which, once sterilization is completed, is removed from the surfaces of the packaging material, e.g. evaporated by heating; and the web of packaging material so sterilized is maintained in a closed, sterile environment, and is folded and sealed longitudinally to form a vertical tube.
The tube is filled continuously downwards with the sterilized or sterile-processed food product, and is sealed and then cut along equally spaced cross sections to form pillow packs, which are then fed to a folding unit to form the finished, e.g. substantially parallelepiped-shaped packages.
The folding unit generally outputs a single row, which is formed by a queue of packages.
A transferring unit is arranged downstream from the folding station, is fed with the single row by an input line and selectively feeds the packages to a plurality of output lines.
Still more precisely, the transferring unit transfers the packages from the input line to one prescribed output line.
The input line and the output lines extend along a first direction. The output lines are parallel to each other and are aligned along a second direction, which is orthogonal to the first direction.
An example of the transferring unit is known from EP-A-1439140.
An embodiment of transferring unit known from EP-A-1439140 substantially comprises:                an active conveyor, which is movable along the first direction and is interposed between the input line and the output lines;        a belt sequencing device, which accelerates, one after the other, the packages of the queue, so as to separate them by gap; and        a distributing system, which is interposed between the sequencing device and the output lines.        
In greater detail, the distributing system defines a conveying channel for the separated packages. The channel has a fixed input opening fed by the sequencing device with the single row of separated packages, and an output opening. The output opening is movable relative to the input opening parallel to both the first direction and to the second direction, so as to be aligned with the prescribed output line along the first direction.
The distributing system substantially comprises, proceeding from the input opening to the output opening of the channel:                a pair of first conveyors facing each other and defining the input station of the channel; and        a pair of second conveyors facing each other, and each comprising a first portion and a second portion.        
In detail, each first conveyor has a first end hinged to a frame about a first axis, and a second end hinged to the first portion of the respective second conveyor about a second axis. First axes and second axes are orthogonal to the first direction and the second direction and vertical.
The second portions of the second conveyors define, on the opposite side of the respective first portion of the second conveyors, the output opening of the channel.
Furthermore, the second portion of each second conveyor may be retracted or extended relative to the corresponding first portion and along the first direction.
In particular, both the first conveyors and the second conveyors are belt conveyors.
Still more precisely, the transferring unit of EP-A-1439140 comprises:                a first motor, which is connected to both the first portions of the second conveyors, and which integrally displaces the first portions along the second direction towards the prescribed output line, so causing the first conveyors to be angled with respect to the first direction and to rotate about the first axes and the second axes; and        a second motor, which is connected to both the second portions of the second conveyors, and which integrally displaces the second portions along the first direction, so as to extend or retract the second portions from/into the respective first portions.        
In particular, the first motor and the second motor are fixed to a frame of the transferring unit.
The operation of the first motor and the second motor arranges the first conveyors with a given angle relative to the first direction, whereas the second conveyors remain parallel to the first direction and are aligned with the prescribed output line.
In other words, the angle between the input line and the prescribed output line is recovered by the inclination of the first conveyors with respect to the first direction.
Moreover, the first conveyors remain parallel to each other, because they are hinged at their first and second ends to the frame and the distance between the second conveyors is kept constant. In other words, the first conveyors form an articulated parallelogram.
Accordingly, the distance between the first conveyors varies with the position of the output opening of the channel along the second direction.
As a consequence, the width of the channel in the region defined by the first conveyors varies with the position of the output opening along the second direction.
That variation of the width of the channel generates the risk that the packages change their orientation, when conveyed by the first conveyors.
This is because the width of the channel corresponds to the width of the packages, only for a given inclination angle of the first conveyors relative to the first direction.
Accordingly, when the angle of the first conveyors relative to the first direction is different from the given one, the packages are no longer fully controlled by the first conveyors.
In order to contain that risk, the transferring unit of EP-A-1439140 has a very long channel and the first and the second conveyors have thick belts.
A need is felt within the industry to render the orientation of the packages as controllable as possible, while reducing the length of the distributing assembly and/or without relying on thick belts.
Furthermore, a need is felt within the industry to reduce the variations of angles of the channel with respect to the first direction, in order to further reduce the risk that the orientation of the packages varies.
The transferring unit of EP-A-1439140 also comprises a third motor, which drives in rotation a pairs of pulleys of the first conveyors.
These pulleys are arranged close to the input station of the channels. Furthermore, the belts of the first conveyors drive the belts of the second conveyors.
Accordingly, the packages, when travelling along the channel from the input opening to the output opening, cooperate with driven branches of the belts of the first conveyors and the second conveyors.
A need is also felt within the industry to increase the belt tension of the branches of the first and the second conveyors which cooperate with the packages.
Finally, the belts of the sequencing device are spaced from the belts of the distributing system.
Accordingly, the packages are not continuously guided, when transferred from the sequencing device to the distributing system.
A need is therefore felt within the industry to continuously guide the packages, when the latter are transferred from the sequencing device to the distributing system.